324 lines
11 KiB
C
324 lines
11 KiB
C
/* A representation of vector permutation indices.
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Copyright (C) 2017-2021 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "vec-perm-indices.h"
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#include "tree.h"
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#include "fold-const.h"
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#include "tree-vector-builder.h"
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#include "backend.h"
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#include "rtl.h"
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#include "memmodel.h"
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#include "emit-rtl.h"
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#include "selftest.h"
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#include "rtx-vector-builder.h"
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/* Switch to a new permutation vector that selects between NINPUTS vector
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inputs that have NELTS_PER_INPUT elements each. Take the elements of the
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new permutation vector from ELEMENTS, clamping each one to be in range. */
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void
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vec_perm_indices::new_vector (const vec_perm_builder &elements,
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unsigned int ninputs,
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poly_uint64 nelts_per_input)
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{
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m_ninputs = ninputs;
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m_nelts_per_input = nelts_per_input;
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/* If the vector has a constant number of elements, expand the
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encoding and clamp each element. E.g. { 0, 2, 4, ... } might
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wrap halfway if there is only one vector input, and we want
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the wrapped form to be the canonical one.
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If the vector has a variable number of elements, just copy
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the encoding. In that case the unwrapped form is canonical
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and there is no way of representing the wrapped form. */
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poly_uint64 full_nelts = elements.full_nelts ();
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unsigned HOST_WIDE_INT copy_nelts;
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if (full_nelts.is_constant (©_nelts))
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m_encoding.new_vector (full_nelts, copy_nelts, 1);
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else
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{
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copy_nelts = elements.encoded_nelts ();
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m_encoding.new_vector (full_nelts, elements.npatterns (),
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elements.nelts_per_pattern ());
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}
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unsigned int npatterns = m_encoding.npatterns ();
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for (unsigned int i = 0; i < npatterns; ++i)
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m_encoding.quick_push (clamp (elements.elt (i)));
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/* Use the fact that:
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(a + b) % c == ((a % c) + (b % c)) % c
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to simplify the clamping of variable-length vectors. */
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for (unsigned int i = npatterns; i < copy_nelts; ++i)
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{
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element_type step = clamp (elements.elt (i)
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- elements.elt (i - npatterns));
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m_encoding.quick_push (clamp (m_encoding[i - npatterns] + step));
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}
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m_encoding.finalize ();
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}
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/* Switch to a new permutation vector that selects the same input elements
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as ORIG, but with each element split into FACTOR pieces. For example,
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if ORIG is { 1, 2, 0, 3 } and FACTOR is 2, the new permutation is
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{ 2, 3, 4, 5, 0, 1, 6, 7 }. */
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void
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vec_perm_indices::new_expanded_vector (const vec_perm_indices &orig,
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unsigned int factor)
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{
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m_ninputs = orig.m_ninputs;
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m_nelts_per_input = orig.m_nelts_per_input * factor;
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m_encoding.new_vector (orig.m_encoding.full_nelts () * factor,
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orig.m_encoding.npatterns () * factor,
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orig.m_encoding.nelts_per_pattern ());
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unsigned int encoded_nelts = orig.m_encoding.encoded_nelts ();
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for (unsigned int i = 0; i < encoded_nelts; ++i)
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{
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element_type base = orig.m_encoding[i] * factor;
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for (unsigned int j = 0; j < factor; ++j)
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m_encoding.quick_push (base + j);
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}
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m_encoding.finalize ();
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}
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/* Rotate the inputs of the permutation right by DELTA inputs. This changes
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the values of the permutation vector but it doesn't change the way that
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the elements are encoded. */
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void
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vec_perm_indices::rotate_inputs (int delta)
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{
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element_type element_delta = delta * m_nelts_per_input;
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for (unsigned int i = 0; i < m_encoding.length (); ++i)
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m_encoding[i] = clamp (m_encoding[i] + element_delta);
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}
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/* Return true if index OUT_BASE + I * OUT_STEP selects input
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element IN_BASE + I * IN_STEP. For example, the call to test
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whether a permute reverses a vector of N elements would be:
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series_p (0, 1, N - 1, -1)
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which would return true for { N - 1, N - 2, N - 3, ... }.
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The calls to test for an interleaving of elements starting
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at N1 and N2 would be:
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series_p (0, 2, N1, 1) && series_p (1, 2, N2, 1).
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which would return true for { N1, N2, N1 + 1, N2 + 1, ... }. */
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bool
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vec_perm_indices::series_p (unsigned int out_base, unsigned int out_step,
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element_type in_base, element_type in_step) const
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{
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/* Check the base value. */
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if (maybe_ne (clamp (m_encoding.elt (out_base)), clamp (in_base)))
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return false;
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element_type full_nelts = m_encoding.full_nelts ();
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unsigned int npatterns = m_encoding.npatterns ();
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/* Calculate which multiple of OUT_STEP elements we need to get
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back to the same pattern. */
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unsigned int cycle_length = least_common_multiple (out_step, npatterns);
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/* Check the steps. */
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in_step = clamp (in_step);
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out_base += out_step;
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unsigned int limit = 0;
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for (;;)
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{
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/* Succeed if we've checked all the elements in the vector. */
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if (known_ge (out_base, full_nelts))
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return true;
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if (out_base >= npatterns)
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{
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/* We've got to the end of the "foreground" values. Check
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2 elements from each pattern in the "background" values. */
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if (limit == 0)
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limit = out_base + cycle_length * 2;
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else if (out_base >= limit)
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return true;
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}
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element_type v0 = m_encoding.elt (out_base - out_step);
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element_type v1 = m_encoding.elt (out_base);
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if (maybe_ne (clamp (v1 - v0), in_step))
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return false;
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out_base += out_step;
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}
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return true;
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}
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/* Return true if all elements of the permutation vector are in the range
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[START, START + SIZE). */
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bool
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vec_perm_indices::all_in_range_p (element_type start, element_type size) const
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{
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/* Check the first two elements of each pattern. */
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unsigned int npatterns = m_encoding.npatterns ();
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unsigned int nelts_per_pattern = m_encoding.nelts_per_pattern ();
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unsigned int base_nelts = npatterns * MIN (nelts_per_pattern, 2);
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for (unsigned int i = 0; i < base_nelts; ++i)
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if (!known_in_range_p (m_encoding[i], start, size))
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return false;
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/* For stepped encodings, check the full range of the series. */
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if (nelts_per_pattern == 3)
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{
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element_type limit = input_nelts ();
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/* The number of elements in each pattern beyond the first two
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that we checked above. */
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poly_int64 step_nelts = exact_div (m_encoding.full_nelts (),
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npatterns) - 2;
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for (unsigned int i = 0; i < npatterns; ++i)
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{
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/* BASE1 has been checked but BASE2 hasn't. */
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element_type base1 = m_encoding[i + npatterns];
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element_type base2 = m_encoding[i + base_nelts];
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/* The step to add to get from BASE1 to each subsequent value. */
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element_type step = clamp (base2 - base1);
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/* STEP has no inherent sign, so a value near LIMIT can
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act as a negative step. The series is in range if it
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is in range according to one of the two interpretations.
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Since we're dealing with clamped values, ELEMENT_TYPE is
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wide enough for overflow not to be a problem. */
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element_type headroom_down = base1 - start;
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element_type headroom_up = size - headroom_down - 1;
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HOST_WIDE_INT diff;
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if ((!step.is_constant (&diff)
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|| maybe_lt (headroom_up, diff * step_nelts))
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&& (!(limit - step).is_constant (&diff)
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|| maybe_lt (headroom_down, diff * step_nelts)))
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return false;
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}
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}
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return true;
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}
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/* Try to read the contents of VECTOR_CST CST as a constant permutation
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vector. Return true and add the elements to BUILDER on success,
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otherwise return false without modifying BUILDER. */
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bool
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tree_to_vec_perm_builder (vec_perm_builder *builder, tree cst)
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{
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unsigned int encoded_nelts = vector_cst_encoded_nelts (cst);
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for (unsigned int i = 0; i < encoded_nelts; ++i)
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if (!tree_fits_poly_int64_p (VECTOR_CST_ENCODED_ELT (cst, i)))
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return false;
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builder->new_vector (TYPE_VECTOR_SUBPARTS (TREE_TYPE (cst)),
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VECTOR_CST_NPATTERNS (cst),
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VECTOR_CST_NELTS_PER_PATTERN (cst));
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for (unsigned int i = 0; i < encoded_nelts; ++i)
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builder->quick_push (tree_to_poly_int64 (VECTOR_CST_ENCODED_ELT (cst, i)));
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return true;
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}
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/* Return a VECTOR_CST of type TYPE for the permutation vector in INDICES. */
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tree
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vec_perm_indices_to_tree (tree type, const vec_perm_indices &indices)
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{
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gcc_assert (known_eq (TYPE_VECTOR_SUBPARTS (type), indices.length ()));
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tree_vector_builder sel (type, indices.encoding ().npatterns (),
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indices.encoding ().nelts_per_pattern ());
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unsigned int encoded_nelts = sel.encoded_nelts ();
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for (unsigned int i = 0; i < encoded_nelts; i++)
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sel.quick_push (build_int_cst (TREE_TYPE (type), indices[i]));
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return sel.build ();
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}
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/* Return a CONST_VECTOR of mode MODE that contains the elements of
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INDICES. */
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rtx
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vec_perm_indices_to_rtx (machine_mode mode, const vec_perm_indices &indices)
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{
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gcc_assert (GET_MODE_CLASS (mode) == MODE_VECTOR_INT
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&& known_eq (GET_MODE_NUNITS (mode), indices.length ()));
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rtx_vector_builder sel (mode, indices.encoding ().npatterns (),
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indices.encoding ().nelts_per_pattern ());
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unsigned int encoded_nelts = sel.encoded_nelts ();
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for (unsigned int i = 0; i < encoded_nelts; i++)
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sel.quick_push (gen_int_mode (indices[i], GET_MODE_INNER (mode)));
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return sel.build ();
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}
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#if CHECKING_P
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namespace selftest {
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/* Test a 12-element vector. */
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static void
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test_vec_perm_12 (void)
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{
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vec_perm_builder builder (12, 12, 1);
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for (unsigned int i = 0; i < 4; ++i)
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{
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builder.quick_push (i * 5);
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builder.quick_push (3 + i);
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builder.quick_push (2 + 3 * i);
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}
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vec_perm_indices indices (builder, 1, 12);
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ASSERT_TRUE (indices.series_p (0, 3, 0, 5));
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ASSERT_FALSE (indices.series_p (0, 3, 3, 5));
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ASSERT_FALSE (indices.series_p (0, 3, 0, 8));
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ASSERT_TRUE (indices.series_p (1, 3, 3, 1));
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ASSERT_TRUE (indices.series_p (2, 3, 2, 3));
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ASSERT_TRUE (indices.series_p (0, 4, 0, 4));
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ASSERT_FALSE (indices.series_p (1, 4, 3, 4));
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ASSERT_TRUE (indices.series_p (0, 6, 0, 10));
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ASSERT_FALSE (indices.series_p (0, 6, 0, 100));
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ASSERT_FALSE (indices.series_p (1, 10, 3, 7));
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ASSERT_TRUE (indices.series_p (1, 10, 3, 8));
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ASSERT_TRUE (indices.series_p (0, 12, 0, 10));
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ASSERT_TRUE (indices.series_p (0, 12, 0, 11));
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ASSERT_TRUE (indices.series_p (0, 12, 0, 100));
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}
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/* Run selftests for this file. */
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void
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vec_perm_indices_c_tests ()
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{
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test_vec_perm_12 ();
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}
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} // namespace selftest
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#endif
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